MARS CLIMATE ORBITER MISSION STATUS

December 19, 1998 - 11:00 A.M. (PST)

Now eight days past launch, Mars Climate Orbiter is performing well
under the control of its first "housekeeping" sequence, which was
successfully transmitted to the spacecraft and activated yesterday. Deep
Space Network (DSN) coverage of the spacecraft has dropped to three contact
periods per day of roughly four hours each. This level of coverage will
continue out through Jan. 11, 1999 (L+30 days).

This morning commands were successfully transmitted to the spacecraft to
complete the configuring of its software system for early cruise. The
orbiter's autopilot is now programmed to track the Earth with its
medium-gain antenna. The vehicle's orientation will evolve slowly as the
Earth and spacecraft follow their respective orbits around the sun.
Analysis of the spacecraft's power and thermal control subsystems indicate
that it can operate safely in this manner for at least one month, and
probably longer, allowing sufficient time for the flight team to conduct
the initial Mars Polar Lander post-launch operations before returning to
long-range planning for the orbiter.

Preparations are nearing completion for the orbiter's first Trajectory
Correction Maneuver (TCM), designated TCM-1. Testing and verification of
the maneuver commands will be completed later today, with the maneuver
scheduled to begin at 1:30 P.M. PST on Monday, Dec. 21st.

Mars Climate Orbiter Mission Status

December 11, 1998
3:30 p.m. Eastern Standard Time

After a one-day delay, NASA's Mars Climate Orbiter blasted
off launch pad 17A at Cape Canaveral Air Station, FL, at 1:45
p.m. Eastern Standard Time today and hurtled skyward on a 9-1/2-
month flight to Mars to embark on a study of the planet's climate
and current water resources. The 24-hour launch delay will not
change the spacecraft's arrival date at Mars on September 23,
1999, or alter its primary mapping mission.

The spacecraft shot through a breezy, cloud-laced mid-
afternoon sky atop a Delta II launch vehicle on the second day of
the primary launch period with new onboard software to guard
against overcharging the spacecraft's battery. The orbiter team
tested the new software using the Mars Polar Lander spacecraft at
Kennedy Space Center, FL, as a testbed. Mars Polar Lander, which
will join Mars Climate Orbiter at Mars in December 1999, is
currently being processed for launch on January 3, 1999.

Sixty seconds after liftoff, the four solid-rocket boosters
were jettisoned, two at a time, followed by first-stage
separation and second-stage engine ignition. The second-stage
burn lasted approximately 11 minutes, 22 seconds, placing the
spacecraft in a low-Earth orbit at about 189 kilometers (117
miles) above Earth's surface.

Third-stage separation occurred at approximately 2:26 p.m.
EST, followed by a burn of the third-stage engine for 88 seconds.
Once out of Earth's gravitational grasp, the orbiter was
jettisoned from the third stage using the spacecraft's onboard
thrusters to remove all remaining motion. Four minutes later,
the spacecraft's solar arrays were unfolded and pointed toward
the Sun for power. NASA's Deep Space Network complex near
Canberra, Australia, acquired the orbiter's signal at 2:45 p.m.
EST. Spacecraft controllers at Lockheed Martin Astronautics in
Denver, CO, and at the Jet Propulsion Laboratory in Pasadena, CA,
are now assessing the spacecraft's initial performance.

Now on its way to Mars, the Climate Orbiter will rely on its
low-gain and medium-gain antennas for communications with Earth
during the first half of the journey to Mars. Ground-controllers
will track the spacecraft 24 hours a day during the first week of
cruise, then reduce tracking time to 12 hours a day using 34-
meter (112-foot) antennas of the Deep Space Network. Twelve days
into flight, one of the spacecraft's science instruments, the
Pressure Modulator Infrared Radiometer, will be powered on and
acclimated to the environment of space.

The first trajectory correction maneuver to remove errors in
the spacecraft's flight path introduced at the time of launch
will be performed 10 days into the cruise phase, on December 21,
1998. That thruster firing will be the largest and longest of
all four trajectory correction maneuvers, lasting about 15 to 20
minutes and changing the spacecraft's velocity by about 30 meters
per second (67 miles per hour).

Mars Climate Orbiter and Mars Polar Lander are the second
set of spacecraft to be launched in NASA's long-term program of
robotic exploration of Mars.

ROYAL ASTRONOMICAL SOCIETY

2 December 1998

OXFORD AIMS FOR MARS

Scientists from Oxford University have a particular interest in the
latest NASA mission to Mars, having played a major role in the design
and construction of the main payload on board the Mars Climate Orbiter.
The spacecraft, which is scheduled for launch on 10 December, will be
the second in NASAs new Surveyor series of unmanned missions to the Red
Planet.

'Mars Climate Orbiter is particularly significant since it will be the
first mission to Mars with a substantial British component,' said
Professor Fred Taylor of Oxford University's Department of
Atmospheric, Oceanic and Planetary Physics.

The 44kg instrument, named PMIRR (Pressure Modulator Infrared
Radiometer) represents the culmination of more than ten years of
effort aimed at understanding the climate on Mars. A similar
PMIRR instrument carried on a previous NASA spacecraft
known as Mars Observer was lost when the spacecraft failed to
respond to transmissions after it attempted to enter Mars orbit in
1993.

Many of the Mars Observer instruments were rebuilt and flown on
the first Mars Surveyor but PMIRR had to wait because it was too
large to be included. The new instrument has been designed and
built as a collaboration between NASA's Jet Propulsion Laboratory
(JPL) in California and the Department of Atmospheric, Oceanic and
Planetary Physics at Oxford University. Its design is based closely
upon a successful series of instruments developed by Oxford
University for remote sensing the Earth's atmosphere which have
flown on several NASA spacecraft since the early 1970's.

Atmospheric Science

PMIRR's importance lies in the fact that it should provide scientists
withthe most complete overview of Martian weather yet obtained.
From a polar orbit 400 km above Mars. PMIRR will measure the
water content, dust loading and temperature of the atmosphere
over the entire planet by scanning from the surface to an altitude
of 80km (50 miles). The temperature measurements are particularly
important because from these it is possible to learn about atmospheric
circulation and winds, and study the transport of other constituents,
such as water vapour and carbon dioxide, around the planet.

'We're looking to find out how the atmosphere works, how it
contributes toconditions on the surface and how the climate may
have changed in the past,' said Professor Taylor.

Although there are a number of similarities between the way the
atmosphere behaves on Earth and Mars, the thin Martian atmosphere
still holds a number of mysteries. Despite a surface pressure on Mars
which is only about 1% of that on Earth, the carbon dioxide-rich
atmosphere is nevertheless very active. Almost a quarter of the
carbon dioxide seems to condense onto the polar ice caps
during winter.

No liquid water can exist on Mars today, but water is transported
in the atmosphere. By studying how the amount of water varies
with altitude and latitude (distance from the equator) during the
year it is hoped to obtain clues about the location of other, hidden,
water reservoirs, such as subsurface permafrost.

The third extremely significant component of the atmosphere is
dust, which has a considerable impact on the temperature of the
atmosphere and surface. The amount varies from season to
season, and occasionally global dust storms completely obscure
the planet during the southern hemisphere's summer.

Starting with the 1999 Mars Polar Lander, many of the missions
planned for Mars exploration over the next decade involve surface
landers. While meteorological stations on the surface give extremely
valuable measurements of local weather and near surface effects,
the global view obtained by PMIRR will enable scientists to put
this data into a planetary context.

The PMIRR data will eventually lead to more accurate global
models of the Martian environment, a necessary precursor for
future robotic and human exploration missions.

UK Technology

At the heart of the PMIRR design are the pressure modulators
which were developed in Oxford. These are metal cylinders
about 20 cm long inside which the gas pressure is cycled
about 50 times per second. PMIRR carries two modulators
built by Oxford, one holding carbon dioxide and the other
containing water vapour. These are the same gases which are
being measured in the atmosphere.

By measuring the infrared (heat) radiation coming from the
planet after it passes through the gas in the modulator, a signal
is produced which is specific to the gas chosen. This is particularly
useful when remote sensing Mars because the infrared radiation
from the gases is mixed with radiation from the dust which always
seems to be present in the atmosphere.

All of the 9 infrared detectors used in PMIRR were supplied
by GEC-Marconi Infrared in Southampton. These were assembled
into working optical units in Oxford and delivered to NASA/JPL for
installation into the instrument. Almost all of the 52 lenses, filters
and other optics used in PMIRR were supplied by Reading University
Infrared Multilayer Laboratory. The only exceptions are two innovative
"mesh" filters used at long infrared wavelengths which were developed
and built by Queen Mary and Westfield College, London.

Notes:

The Mars Climate Orbiter is due for launch on Dec. 10 on a Boeing
Delta 2 launch vehicle from Cape Canaveral Air Station, Florida.
The orbiter will arrive at the Red Planet in September 1999 and
will circle Mars for a whole Martian year (about 2 Earth years) to
study the atmosphere and climate. Apart from PMIRR, the only
science payload on board is a 4kg colour imager comprising
two tiny cameras.

The Mars Polar Lander is scheduled for launch on Jan. 3 1999.
It will touch down near the planet's South Pole on Dec. 3, 1999.
Riding aboard the cruise stage of the lander are two microprobes
developed by NASA's New Millennium program, under the name
Deep Space 2. The microprobes will be released just before
atmospheric entry, and then will crash into the Martian surface
near the landing site to test 10 advanced technologies and search
for traces of subsurface water ice.

More details of the Mars Climate Observer and Mars Polar Lander
missions can be found on the Internet at the following home
pages:

NASA's Mars Climate Orbiter arrived at Kennedy Space Center today to begin
final preparations for launch. The spacecraft arrived aboard an Air Force
C-17 cargo plane at the Shuttle Landing Facility early this morning
following its flight from the Lockheed Martin Astronautics plant in Denver,
Colo. The launch of the Mars Climate Orbiter is scheduled to occur aboard a
Boeing Delta II (7425) rocket on Dec. 10, 1998.

When it first arrives at the red planet, the Mars Climate Orbiter will be
used primarily to support its companion Mars Polar Lander spacecraft,
planned for launch on Jan. 3, 1999. After that, the Mars Climate Orbiter's
instruments will monitor the Martian atmosphere and image the planet's
surface on a daily basis for one Martian year, the equivalent of two Earth
years. During this time, the spacecraft will observe the appearance and
movement of atmospheric dust and water vapor, as well as characterize
seasonal changes on the surface. The detailed images of the surface
features will provide important clues to the planet's early climate history
and give scientists more information about possible liquid water reserves
beneath the surface.

The spacecraft is to be readied for launch in NASA's Spacecraft Assembly and
Encapsulation Facility-2 (SAEF-2) located in the KSC Industrial Area. Among
the processing activities to be performed in this clean room facility are a
functional test of the science instruments and the basic spacecraft
subsystems.

Checks of the communications system will be performed including a
verification of the spacecraft's ability to send data via the tracking
stations of the Deep Space Network to the Jet Propulsion Laboratory (JPL) in
Pasadena, Calif. and the Lockheed Martin plant in Denver, Colo.

Following these checks, the spacecraft will be fueled with the spacecraft
bipropellants of hydrazine and nitrogen tetroxide and mated to a Star 48
solid propellant upper stage booster. Finally, the combined spacecraft and
upper stage elements will undergo spin balance testing.

Meanwhile, at Launch Complex 17, the Delta II rocket will be undergoing
erection and prelaunch checkout by Boeing on Pad A. The first stage is
scheduled to be installed into the launcher on Oct. 29. Four solid rocket
boosters will be attached around the base of the first stage on Nov. 2. The
second stage will be mated atop the first stage on Nov. 4, and the fairing
will be hoisted into the clean room of the pad's mobile service tower Nov.
6.

The Mars Climate Orbiter with its upper stage booster will be transported to
Complex 17 on Nov. 30 for hoisting atop the Delta and mating to the second
stage. After the spacecraft undergoes a state of health check the next day,
the two halves of the fairing will be placed around it on Dec. 3. Finally,
there will be a mission dress rehearsal.

At liftoff, the spacecraft will weigh 1,418 pounds (3,120 kilograms). It is
7.6 feet (25 meters) high, 6.4 feet (21 meters) deep, and 5.4 feet (18
meters) wide. Power is provided by a single large solar array which is 18.6
feet (61 meters) long and 6.8 feet (22 meters) across. After cruising in
space for 286 days, the spacecraft will be captured in an elliptical orbit
around Mars.

The eight-day primary launch period to achieve an optimum cruise phase and
Mars planetary encounter begins with an instantaneous launch window at 1:56
p.m. EST, Dec. 10. There are two instantaneous windows each day. A
secondary six-day period of launch opportunity begins Dec. 18. The last day
available for launch is Dec. 25.

The 1998 Mars Climate Orbiter and Mars Polar Lander missions are managed by
the Jet Propulsion Laboratory for NASA's Office of Space Science,
Washington, D.C. JPL is a division of the California Institute of
Technology, Pasadena, Calif. Lockheed Martin Astronautics, Denver, Colo.
which built and operates the spacecraft, is JPL's industrial partner in the
mission.